Helpful CCTV Tips

Camera back focus adjustment ensures that a camera's image
remains in focus during changing lighting conditions. This is a common problem
in CCTV installations where one sees a sharp image during daylight but a
blur at night. During bright sunlight, the lens iris is closed and the depth
of field very wide. When the light level drops, the Iris opens and the depth
of field decreases. To reach the optimum focus, the camera needs to be back
focused with the lenss iris fully opened. Proper back-focus adjustment
also holds true for zoom lenses which need to be properly adjusted to hold
focus through the zoom range.

More and more people are moving to DIGITAL BASED CCTV Systems over
the conventional analog VCR based systems. The benefits of using a digital
system, is that it allows the user to replace their switching unit, monitor
and time-lapse recorder with one centralized system, which they can access
and control from several locations. Because the system is automated, one
does not have to swop or replace any video cassette tapes, allowing minimum
intervention from the system controller.

These systems can record video images on the HDD, depending on capacity,
for several weeks. A digital system allows the user to instantly retrieve
relevant data. There is no longer a need for screening through hours of
video tape to find a single frame of video. Data is stored in a database
which can be searched by camera, time, date, alarm-activation or motion.
This saves the user time in identifying the target.

Even at the most basic level digital video images are superior to video
recorded on analog systems. Sharp, crisp images are stored which can be
viewed over and over again without image deterioration.

Yet another
advantage of digital systems is their flexibility of recording modes. Recording
can be done by schedule (ie. time or date), alarm activation or via smart
motion detection.

Faster retrieval times - No more plodding through
hours and hours of videotape. Utilising digital CCTV, users can instantly
retrieve video. Users can rapidly search events by time, date, location
and camera.

Less storage space required - Users may set the system
to record
when motion or other pre-defined events are detected - so there's no
wasted "dead taping". Video is then compressed and efficiently
stored
to a PC's hard drive.

Archiving - Important information can be archived
to FDD, HDD, CD-R
or DVD for later retrieval.

Higher image quality - Digital CCTV provides unbeatable
quality.
Digital video can be easily enhanced and copied over and over without
losing its original quality.

Regular servicing of your VCR , will ensure continued
operation and quality of recordings.

Use only high quality 'branded' tapes

Replace tapes after being used 12 times.

Ensure Time Lapse VCR is suitably hidden in event of
a robbery

Before reviewing a video tape for evidence, make a copy
and review the copy. This ensures the the quality of the original is
preserved, especially when starting, stopping and pausing the tape.

E. Wireless Video Transmission

For outdoor use, transmitter and receiver must be in
line-of-sight.

Determine any possible sources of interference, i.e.
overhead powerlines, wireless LAN networks, transformers, other transmitters
or any other power generating system in close
proximity to the transmitter or receiver.

Avoid trees in the transmission path, as brances can
cause interference.

Ensure proper alignment between transmitter and receiver.

Beware of lightning. Transmitters are often placed on
high masts/roofs, which make them prone to lightning.

Poor weather such as heavy fog and rain can affect transmission.

F. Digital Video Recorder Considerations

It is recommended to connect your DVR and cameras to
an uninterruptable PSU (UPS)

Ensure 1Vp-p video input levels from cameras (not lower
or higher)

Turn off camera AGC

Ensure DVR is suitably secure or hidden in event of
a robbery

Avoid Win98/ME as an operating system, Win2K is the
most stable for PC-based DVRs

For PC-based DVRs, regular HDD defragmentation is recommended
if DVR is used for other user applications. (Not necessary if PC is
dedicated to DVR.)

Ensure enough RAM so that the recording does not get
interrupted.

Recording should be on different hard drive to that
of the operating system and recording software.

One of the biggest issues in the design and usage of
any Closed Circuit Television System is the usable images or video footage
that one can utilise during or after an event.

There are obviously several factors that come into play when determining
this. Factors include quality of installation, video recording resolution,
frame rate, environmental conditions, CCD resolution and sensitivity.
When designing a CCTV system it is important to have focused cameras at
all entry and exit points. Any individuals or vehicles will need to pass
through these points to access or exit the area under surveillance. All
CCTV camera positions have an application or role. These include monitoring
and detection, as well as recognition and identification.

As an aid for the CCTV installer the UK Home Office has published a guideline
in regard to identifying individuals or vehicles. By using this guideline
you will be able to achieve the camera objectives your installation requires.

As an aid for the CCTV installer the UK Home Office has published a guideline
in regard to identifying individuals or vehicles. By using this guideline
you will be able to achieve the camera objectives your installation requires.

Another key aspect of CCTV Systems is installing cameras
that provide usable images in the required lighting conditions. This ranges
in extreme from a brightly lit supermarket to a parking lot, lit only
by the moon. Camera manufacturers normally provide minimum illumination
specifications for their cameras in the best case scenario. Factors that
effect the performance of CCTV camera include the following.

Lens Aperture - Lenses in fact allow only a small
percentage of light to reach the camera’s sensor, this is further
effected by the
aperture of the lens to be used. An F1.0 lens allows 20%, an F1.4 allows
10% and F2.0 only allows 5% passed.

Lens Quality - The quality of the lens determines
the efficiency of the light that is transmitted through the lens. Your
image quality will be much better when using an aspeherical lens, inplace
of a standard lens which will not handled the light as efficiently.

Camera Housing - The amount of light reaching a camera’s
sensor can be reduced by approx 30% when passing through a
housing’s glass window.

Surface Reflection - Different surfaces have varying
percentages of reflectance. Therefore it is better for a camera’s
sensitivity to be focused on a white washed wall (60%) than an empty
tarred parking lot (5%). Most manufacturers provide figures using the
highest reflectance target surface (90%).